During surgical procedures performed in patients with a variety of cardiovascular and pulmonary diseases, and during experimental pulmonary transplantation, periods of hypoxia, abnormal pulmonary blood flow, and other conditions are induced which may alter the normal metabolic and regulatory processes of pulmonary tissue. The high incidence of postoperative pulmonary complications indicates the importance of investigating these problems. In addition, there is a need for improved methods of preserving the lung for transplantation. Utilizing surgical techniques and well-established methods for studying substrate utilization and Krebs cycle enzyme intermediate products, we will attempt to elucidate the normal metabolic and regulatory processes of pulmonary tissue and compare these data with alterations induced by surgical manipulation, and by attempts to preserve pulmonary tissue. Data regarding normal pulmonary metabolism would also be a prerequisite for exploration of causative factors and mechanisms leading to diseases of the respiratory tract. Following completion of in vitro animal studies in which the major components of pulmonary metabolism will be elucidated, a comparison will be made with human pulmonary tissue in vitro.